Obese teenagers have twice the risk of developing bowel cancer by the time they are middle-aged, according to a new study published in the journal Gut.

Obesity and inflammation among adults have been linked with an increased risk of bowel cancer; this type of cancer affects mostly men. But, little information is available about how systemic inflammation might affect one during late adolescence. Therefore, the researchers of the study surveyed around 240,000 Swedish men who had been conscripted into the military between 16 and 20 years of age in 1969-76.

These men had a health check when they were enlisted; their weight, height and erythrocyte sedimentation rate (ESR) level (which is an indicator of systemic inflammation) were noted. The participants were monitored for bowel cancer up to 2010.

It was found that when conscription was done, 81 % were of normal weight, around 12 % of them were underweight, around 5 % were moderately overweight, 1.5% were very overweight, and 1% were obese. It was seen that over the period of 35 years, 885 of the men had developed bowel cancer (with 384 of them being rectal cancers).

When those who were very overweight (BMI 27.5 – 30) were compared with those falling within the normal range (BMI 18.5 – 25), it was seen that they were two times more likely to have bowel cancer.

Obese as young adults (with BMI more than 30) was linked with a 2.38 higher risk of developing bowel cancer.

Those with a high ESR among the men who did not have any known inflammatory bowel disease at the time of conscription had a 63 % greater risk of having bowel cancer than those with lower ESR.

The researchers state that while their results are not conclusive, they suggest that BMI and inflammation during adolescence may impact on the person’s tendency to develop bowel cancer.